Hello, I use AUDACITY software to rip vinyls and tapes to mp3. It happens that when I rip vinyls, the digital track sound is perfect but the volume is VERY LOW. I must say I donīt have much idea of using this kind of software and I must be doing something wrong.

Can anyone tell me what should I do to increase the volume of the digital tracks (editing??) with AUDACITY (or another free software)?

captainretardo and HotBlack have it. If you have a receiver with a Phono input and a line-out you do not need a preamp, as the receiver already has one. Otherwise you will need to get a receiver with a Phono jack (check thrift stores) or a preamp. From there you can use the volume slider in Audacity (it's near the top with a little microphone icon next to it) and Amplify to set the volume._________________Basar North America / Promethean Burn: http://www.thebasar.org/NorthAmerica

pre-amp is essential for ripping vinyls.
if you use line to rip tapes, the volume of the player should do it.

for vinylripping I had nice results with Numark TT USB(built-in pre-amp + USB out) and Audacity.
It's great for ripping Vinyls to mp3 but sucks ass when you hook it up to speakers - so it's probably more a USB-only Solution.
Will set you back ~$100.